Original subtitles

The Paranal Observatory in Chile

boasts one of the world's most beautiful views

of the starry night sky.

It was here in 2009 that a surprising discovery was made

regarding a particular star.

This star is a 1,000 times bigger than the Sun,

and is covered in bright red flames.

It also has a bump-like protrusion,

and that's not all.

As I said, I mean it can be very close

to collapse and finally explosion.

It can be even at an age of 99.9% of its life.

We are in Hida City in Japan.

The star may explode any day now,

and preparing for this is a gigantic

observation device called Super Kamiokande.

It should detect signs of the explosion

faster than anywhere else in the world.

If signs of an explosion are detected,

telescopes around the world will turn to the star.

The star that's capturing the attention of the

astronomers worldwide is the Red Giant in Orion.

Betelgeuse.

It's not the explosion at its death will be

300 million times brighter than the Sun.

Furthermore, it is only 640 light years away.

On the grand scale of the universe,

it's a short distance from Earth.

Some scientists warn the explosion may even

spell danger for Earth.

If it is going to be produce a Gamma Ray burst

and we're looking straight down the jet of radiation.

Betelgeuse, the Red Giant.

What is happening now on this star

and what will happen at the moment of its death.

We investigate Betelgeuse, a star on the brink of death.

Roppongi, Tokyo.

The city at night,

viewed from the top of a 240-meter high skyscraper.

The city nightscape is not the only view to be enjoyed.

Guides are on hand to explain the stars in the night sky.

With the city's bright lights,

it's not easy to find the constellations.

But there is one constellation that stands out

more than the rest.

Orion.

It's identified by the three stars in a row,

and the four bright stars surrounding them.

In ancient Greek mythology,

Orion was a brave hunter armed with a club,

who died and ascended to the heavenly skies.

Today's show features the bright red star

Betelgeuse.

We begin by looking at the position of each star

that makes up the constellation.

The stars appear to be on the same plane,

but in fact are at widely varying distances from Earth.

Betelgeuse is 640 light years away,

making it Orion's second closest star to Earth.

200 years ago, an odd discovery

was made about the star.

It took place on the Cape of Good Hope,

on the southern tip of Africa.

The British established an observatory here

in the 19th century.

At the time, accurate positioning of the stars

was vital for navigating the seas.

The Observatory was built to study the stars

visible from the southern hemisphere.

The British astronomer Sir John Herschel

was fascinated by the bright Betelgeuse

and recorded observations of the star.

Herschel noted the stars in order of brightness,

and noticed something rather strange.

These are the results of four years of observation.

Orion here refers to Betelgeuse.

In March 1836, Betelgeuse was the fourth brightest star,

yet eight months later in November,

it was the brightest.

He discovered that sometimes the star grew dimmer,

and other times brighter.

Why did its brightness vary?

So began the quest to unravel the mysteries of Betelgeuse.

80 years later in 1920, a new discovery was made.

This time it was at the Mount Wilson Observatory

just outside Los Angeles.

The physicist Albert Michelson thought the varying

brightness of Betelgeuse was perhaps caused by

changes in its size.

Michelson attached the device called an interferometer

to the end of a large telescope

and attempted to directly measure the size of Betelgeuse.

An interferometer uses two mirrors to reflect

the light from the star,

and then combines the two beams.

When the mirrors are close together,

stripes known as an interference fringe pattern

appear on the star's image.

As the gap between the mirrors widen,

the stripes gradually fade.

The stripes disappear completely when the two mirrors

are exactly aligned with the outer edges of the star.

This distance for Betelgeuse is known,

and so it's possible to calculate its diameter

from its angular distance at this point.

From these observations,

Michelson concluded that Betelgeuse was a giant star

300 times larger than the Sun.

But the mystery of its varying brightness remained.

It was about 40 years later that the puzzle was solved.

Guy Perrin is researching Betelgeuse

at the Paris Observatory.

Perrin uses results from the latest observations

to explain the size of Betelgeuse in the following way:

Detailed observations suggest Betelgeuse's diameter

could be as wide as 1.4 billion kilometers.

That's 1,000 times greater than the Sun.

Placed at the center of our Solar System,

it would surpass the Earth's orbit,

and reach as far as Jupiter.

What's more, it has changed in size

by more than 100 million kilometers.

The giant star changes its brightness as it pulsates.

In fact, this pulsation foreshadows the star's future fate.

Thick stars, which shine by their own light,

are born and die just like humans.

Stars are born out of clouds of gas floating in space.

The gas gathers under its own gravity,

and when its core temperature hits 10 million degrees,

it starts to shine and a star is born.

A star spins most of its life shining constantly

in its steady phase.

The Sun is presently in this stage.

But even the Sun will eventually reach the end of its life,

and gradually expand turning red.

This is when a star becomes a Red Giant.

With a star like Betelgeuse,

whose mass is more than eight times the Sun,

it expands even further as it draws nearer to death

and becomes a Red supergiant.

Betelgeuse is coming to the end of its life.

Scientists around the world are carrying out research

to reveal the giant star's true shape.

Keiichi Ohnaka is based at the Max Planck

Institute for Radio Astronomy in Germany.

Since moving to Germany in 2000,

he has been studying dying stars.

In 2009, Ohnaka made a surprising discovery

about Betelgeuse's shape.

He made his observations at the

Paranal Observatory in Chile.

At an altitude of 2,600 meters,

and with 350 clear nights per year,

it is the ideal location for astronomical observation.

This is the Very Large Telescope Interferometer.

Three telescopes of 1.8 meter aperture

housed in round domes are combined

to make detailed observations.

It works on the same principle as the device used

by Michelson in 1920, but it's much more powerful.

The telescopes can be placed up to 130 meters apart.

Placing the telescopes this far apart produces images

higher in resolution than ever before.

The images of Betelgeuse captured by the three telescopes

are laid on top of each other.

A black vertical stripe appears.

This is the interference fringe pattern.

What drew Ohnaka's attention was this part.

There is a kink in the black stripe.

Further investigation revealed something unexpected.

Normally, spherical stars produce symmetrical graphs.

In Betelgeuse's case however,

the left side of the graph is significantly raised.

What can this mean?

Ohnaka grappled with this conundrum for six months,

and finally reached a conclusion no one

could ever have imagined.

Ohnaka concluded that the asymmetry in the graph

was caused by a bump sticking out of Betelgeuse.

Ohnaka explains the star's shape

that he uncovered from the observation results.

So Betelgeuse is massive, 700 million kilometers wide,

and 40 million times bigger than the Sun.

And unlike normal spherical stars,

it has an irregular shape because of its bump.

But what caused this huge bump to form?

One scientist is proposing that the answer

lies in the star's interior.

Andrea Chiavassa from the Free University of Brussels

is using not observations,

but calculations done on a super computer to try

and decipher the mystery of Betelgeuse's bump.

He has calculated how he travels out

from the center of the star

and how the gas moves over time.

This is how Betelgeuse looks

according to Chiavassa's calculations.

Its surface is covered in patterns

800 million kilometers wide.

And here and there, pockets of gas rise

and then sink back down.

According to Chiavassa's calculations,

the heat generated inside the star

has created convection currents hundreds of times wider

than the Sun's diameter.

This is an actual image of the Sun's surface.

Like Betelgeuse, there are convection currents.

But they are 800,000 times smaller.

The difference is due to the internal structure

of the two stars.

In the Sun, convection currents

only occur near the surface.

With Betelgeuse, on the other hand,

the convection currents almost reach the

center of the giant star.

This is why even the convection currents

visible on the surface are so large.

What's more, the currents are moving

at an astounding speed.

According to Chiavassa's calculations,

Betelgeuse's convection currents are rising

at a speed of 30 kilometers per second.

The gravity of the surface is quite low,

as it's so far from the center of the star.

Gas carried up by the convection currents

rising at great speed is what's creating the bump.

Betelgeuse's odd shape was caused by the star

expanding with age

and by the shear force of its massive convection currents.

In 2006, Akari, a Japanese infrared

astronomy satellite was launched.

Using infrared invisible to the naked eye,

it can survey clouds of gas and dust that float in space.

These are images of Betelgeuse captured by Akari.

Let's combine these four images

taken with different filters.

This reveals a spherical cloud of gas and

dust enveloping Betelgeuse.

It is three light years wide,

20,000 times greater than Betelgeuse's diameter.

The huge amount of gas

and dust that can be seen here

is thought to have been emitted by Betelgeuse.

But it was unknown how Betelgeuse

expelled so much gas and dust.

Trying to decipher this mystery is Perrin

of the Paris Observatory.

Perrin set about observing the area around Betelgeuse

and the gas it emits.

But it's not an easy task to magnify

and examine the area surrounding Betelgeuse.

This is because there is turbulence

in the Earth's atmosphere.

When there is turbulence,

the image is distorted making it hard

to accurately capture the gas and dust that the star emits.

Perrin solved this problem with a clever idea.

This is a lucky imaging experiment.

This card here will be the star,

and the pool here will be the atmosphere

with random motions that destroys the image quality.

So we will put the card in the water

and try to take the best image possible.

The technique of lucky imaging consists in taking

many many pictures until we get

the right picture where the turbulence,

or here the pool is the most stable possible

so that the image is the best possible.

And we will repeat that for many

many times during the night.

Perrin calls the image taken the exact moment

there is no turbulence the lucky image.

Let's look at the actual photos taken.

Continuous shots are taken as a high shutter speed.

In every few hundred photos,

there is one clear image with no distortion.

This is the lucky image that Perrin is after.

But in reality, the light from a star is limited.

To take images at a high shutter speed,

you need a gigantic telescope that can gather

a large amount of light.

So Perrin headed to the Paranal Observatory in Chile.

There are some other big telescopes like these ones,

but this is a unique place in the sense that

we have four telescopes in the same Observatory

with a multitude of instruments that can be used

so that you can make every observation as you would

think of in modern optical astronomy.

This is the Observatory's

Very Large Telescope or VLT for short.

With mirrors 8.2 meters in diameter,

it's one of the world's largest telescopes.

Using this, it's possible to capture at high shutter speeds

the faint gas surrounding Betelgeuse.

Perrin checks the images freshly captured by the telescopes.

The red star that appears on the screen is Betelgeuse.

So what we see here are

images of Betelgeuse through turbulence.

So this is why they're wobbling.

And sometimes they are much sharper than

some others and that's what we call lucky imaging.

The star seems to be constantly moving.

Is there a lucky image in there somewhere?

Perrin set the shutter speed at 7/1000 of a second

and in one night captured over a million images of the star.

The images were then taken back to the

Paris Observatory for analysis.

Perrin and his team have also devised a way to pick out

just the lucky images from the million images of Betelgeuse.

They turn their attention to the

brightest part of the images.

When an image is distorted by the atmosphere,

light is scattered and the image is less bright.

So by comparing the brightest spot of each image

and choosing only the brightest images,

Perrin's team can separate out all the lucky images.

Furthermore, by combining all the lucky images,

it's possible to capture even the faintest, smallest detail.

This is the face of Betelgeuse that Perrin unmasked

from his million images.

The orange ball is Betelgeuse,

and the blue veil is the huge quantity of gas

and dust released by the star.

At last, we have an image that captures the star

expelling gas and dust into space.

Unexpectedly, the gas and dust are not emitted

in a concentric circle but in three different directions.

The furthest tip extends four billion

kilometers from the star.

In terms of the Solar System,

this is about the distance between the Sun and Neptune.

The image also revealed that a clump of gas and dust

had broken off from the outer edge.

This was how Betelgeuse was releasing the high volume

of gas and dust that the

infrared satellite Akari had captured.

The red giant with its swelling bump expels a vast quantity

of gas and dust into the space around it.

The dynamic activity of the star betrays how close it is

to the end of its life.

The death of Betelgeuse is drawing ever closer.

What will happen when it dies?

Hans-Thomas Janka has spent 25 years researching

the final years of a star at Germany's

Max Planck Institute for Astrophysics.

Janka uses an experiment to simulate the death of a star.

We will do a little experiment

of how a supernova works.

How we think a supernova works.

Small container which I will fill

and then we put some water in it.

You see what happens is, of course,

that there's sparkling bubbles coming and gases.

And then we will see how it evolves.

There's pressure building up,

and in the end we will see whether the lid

stays on this container.

So we see this is the way

how we think explosions work.

Janka believes Betelgeuse will also be unable

to withstand the immense pressure

and will finally explode.

The massive explosion of a gigantic star is something the

universe has seen countless times in its long history.

1987 saw a massive explosion of a star

in a neighboring galaxy,

The Large Magellanic Cloud.

The explosion of the star has great repercussions for us.

Thick stars like our Sun emit light as a result of

nuclear fusion taking place in their core.

A star is mostly made up of the

simplest of the elements, Hydrogen.

The high temperature and pressure inside a star's core

cause Hydrogen to fuse into Helium.

This creates energy making the star shine brightly.

This is the present state of our Sun.

After a star has shown for a long period of time,

the Hydrogen in its core is eventually exhausted.

And then, instead of Hydrogen,

the Helium start fusing with each other.

This produces Carbon, Oxygen,

and other new elements.

The core temperature rises

and the star begins to expand.

And so begins its transformation into

a red giant like Betelgeuse.

Finally, when Iron is created, the nuclear fusion stops.

The star can no longer support its own mass

and starts to rapidly collapse.

The pressure in the star's core becomes so immense

it causes a massive explosion.

When the shockwave moves out of the surface of the star,

we call the phenomenon the Supernova.

Event has observed. We can see this is

spectacularly bright celestial phenomenon.

When a Supernova explodes,

the huge amount of energy generated creates

elements heavier than Iron and scatters them all around.

The elements created by the star float abound in space.

Over a long period of time,

elements gradually gather together once more.

And out of these, planets like Earth are born.

And furthermore, life in its various forms.

It's all thanks to the explosion of a dying star

that we are here today.

This is Cassiopeia A, the remnant of a massive star

that exploded as a Supernova.

It's possible to make out the various elements

produced by the star.

The red is Iron, and the green is Silicon.

This is another Supernova remnant, the Crab Nebula.

The cloud of gas and dust is spreading

at a speed of 1,300 kilometers per second.

In this way, elements are scattered

across the universe when stars explode.

In all of recorded history,

only seven Supernova explosions

visible to the naked eye have been witnessed.

The farthest away was SN 1987A,

a Supernova discovered in 1987

in the large Magellanic Cloud.

It is 160,000 light years away.

The Crab Nebula is the closest to us,

but it's still 6,500 light years from Earth.

In comparison, Betelgeuse is a mere 640 light years away.

If Betelgeuse becomes a Supernova,

it would be the closest explosion we have ever faced.

At such a close proximity,

will the Supernova explosion of Betelgeuse

pose any threat to Earth?

Clues to help us answer this question

can be found in Argentina.

It's a two hour drive from the northern city

of San Juan beyond the ravines.

Geologists from the National University of Cordoba

in Corboda province guide us to the site.

400 million years ago, dinosaurs had yet to roam the Earth.

Apart from some moss growing on the ground,

few life forms existed.

Vaccari has found something.

It is a fossil of a Trilobite.

At the time these strata were formed,

the sea was full of many different organisms

and Trilobites in particular flourished.

There were species that lived deep in the sea,

and others that lived near the surface.

The sea was full of Trilobites of all different types.

When Trilobite fossils from different

geological strata are compared,

an interesting fact comes to light.

In strata more than 440 million years old,

both deep sea and shallow water species are found.

But in strata less than 440 million years old,

only deep water species are found.

One scientist believes that a Supernova explosion

caused the extinction of the shallow water Trilobites.

Brian Thomas is an astrophysicist at

Washburn University in America.

At the Ordovician extinction about 440 million years ago,

the most abundant life was Trilobites.

The main reason for that is that the Ozone depletion

is a radiation event which directly affects the organisms.

When a massive star explodes as a Supernova,

it releases a powerful burst of radiation

in the form of Gamma Rays.

Using theoretical calculations,

Thomas can show what changes occur to the Earth's

environment when hit by a burst of Gamma Rays.

This figure here shows the depletion

in Ozone over the globe.

So there's a rapid drop off in the Ozone layer,

and that reaches about 30-35% total.

And that will increase slowly recovering

over about ten years.

Here is what Thomas thinks happened

to the Trilobites.

Earth is protected from the Sun's powerful Ultraviolet Rays

by the Ozone layer.

When Gamma Rays produced by a Supernova explosion hit Earth,

the Ozone layer is destroyed.

This allows the Sun's harmful rays to beat down on the land

and the surface of the sea.

Thomas believes this killed off all the Trilobites

near the surface of the sea, but those deeper down,

where the UV rays couldn't reach, survived.

Once the Ozone is depleted, Ultraviolet light from the Sun

comes through the atmosphere

and organisms are exposed to this Ultraviolet light

will have their DNA and other molecules like proteins

damaged by this particular radiation.

That can cause death.

Thomas argues that the death of a gigantic

star had huge repercussions on life

on Earth in ancient times.

The explosion of Betelgeuse is thought to be imminent,

but are we in any danger?

Past research has shown that when a star dies,

powerful Gamma Rays are released at an angle of

less than two degrees from the axis of rotation.

So the key lies in the direction of Betelgeuse's axis

in relation to Earth.

Observations were carried out to measure

Betelgeuse's rotational axis.

The Hubble Space Telescope was used to

investigate the giant star.

It measured the speed at which certain points

on the star's surface were moving.

This revealed for the first time ever

Betelgeuse's axis of rotation.

The star's axis misses Earth by 20 degrees.

Fortunately, if this is the pole Betelgeuse,

and it represents the way the jet would be oriented,

the Earth is not directly focused along that beam.

It's actually off by about 20 degrees,

so that jet would go off into space and miss us entirely.

When Betelgeuse explodes,

it looks like Earth will be safe from harm.

What would we be able to see

from Earth when Betelgeuse explodes?

Kenichi Nomoto's team at the University of Tokyo

has used theory based calculations to scientifically show

how Betelgeuse will change in color, temperature,

and shape when it explodes.

Here is a simulation of the results.

The final moments have arrived for Betelgeuse,

Orion's red super giant.

Its color changes from red to blue

as its temperature shoots up.

One hour later, Betelgeuse burns more brightly

than any other star

and no one can fail to notice this change.

Three hours after the explosion,

the star's brightness intensifies until it is around

100 times brighter than the full moon.

Even during the day, it dazzles in the blue sky.

It is predicted this brightness will

continue for three months.

All around Betelgeuse, the gas that the star

emits as it dies reflects the intense light

of the Supernova and glows brightly.

Four months later, the star starts changing color again.

As the temperature falls, it changes from blue to orange.

The gas swabs the star layer upon layer

like a flower in bloom.

Eventually, as the temperature drops further,

the star turns red and then gradually fades.

Four years later, Betelgeuse is no longer

visible to the naked eye.

Orion has finally lost its giant star.

A few hundred years later,

it should be possible to see the scattered remnants

of Betelgeuse and the nebular of gas

reflecting light in the far distance.

Since the dawn of history,

we have never seen a Supernova explode so near.

But when will this happen?

In January 2011, an article became a

hot topic of discussion on the internet.

It claimed that Betelgeuse will explode in 2012.

But no one really knows.

A facility in Japan with the ability to identify the

explosion before it's visibly observed

is drawing attention from around the world.

It is located 1,000 meters underground

among the mountains of Gifu prefecture.

This is the Super Kamiokande,

an apparatus that detects particles called Neutrinos

that fly in from space.

Its tank is lined with more than 10,000 detectors.

Just before a Supernova explodes,

a flood of Neutrinos is released from the star's core.

The Neutrinos from Betelgeuse will collide with the water

inside Super Kamiokande's tank and emit countless

flashes of blue light.

At the earliest, the explosion may happen

just a few hours after these flashes occur.

At the facility, training is being carried out

to ensure they will detect the explosion.

When a large number of Neutrinos is detected,

a video conference is held where scientists around the world

and the data is analyzed.

As soon as the Supernova explosion is confirmed,

observatories worldwide are notified.

Scientists around the world are waiting with baited breath

for Betelgeuse to explode.

It's near enough to be a spectacular spot in the sky

if the Supernova explodes.

We will probably see it during daytime.

It would be fantastic to see that.

To see such a big explosion, very bright.

I would really love to see that in my lifetime. Absolutely.

Betelgeuse has fascinated us with its bright red glow.

It is a fierce giant bearing a huge bump

and emitting dust and gas with staggering force.

And soon it will meet its death in a massive explosion.

When will its final hour arrive?

At that historic moment, humankind will witness

yet another undiscovered truth.